47,347 research outputs found

    Determinants of project success

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    The interactions of numerous project characteristics, with particular reference to project performance, were studied. Determinants of success are identified along with the accompanying implications for client organization, parent organization, project organization, and future research. Variables are selected which are found to have the greatest impact on project outcome, and the methodology and analytic techniques to be employed in identification of those variables are discussed

    NASA micromin computer Monthly progress letter, Jan. 1967

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    Microminiature circuit development for flight control computer

    Transport in Graphene Tunnel Junctions

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    We present a technique to fabricate tunnel junctions between graphene and Al and Cu, with a Si back gate, as well as a simple theory of tunneling between a metal and graphene. We map the differential conductance of our junctions versus probe and back gate voltage, and observe fluctuations in the conductance that are directly related to the graphene density of states. The conventional strong-suppression of the conductance at the graphene Dirac point can not be clearly demonstrated, but a more robust signature of the Dirac point is found: the inflection in the conductance map caused by the electrostatic gating of graphene by the tunnel probe. We present numerical simulations of our conductance maps, confirming the measurement results. In addition, Al causes strong n-doping of graphene, Cu causes a moderate p-doping, and in high resistance junctions, phonon resonances are observed, as in STM studies.Comment: 22 pages, 5 figure

    Fluctuating loops and glassy dynamics of a pinned line in two dimensions

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    We represent the slow, glassy equilibrium dynamics of a line in a two-dimensional random potential landscape as driven by an array of asymptotically independent two-state systems, or loops, fluctuating on all length scales. The assumption of independence enables a fairly complete analytic description. We obtain good agreement with Monte Carlo simulations when the free energy barriers separating the two sides of a loop of size L are drawn from a distribution whose width and mean scale as L^(1/3), in agreement with recent results for scaling of such barriers.Comment: 11 pages, 4 Postscript figure

    Is All Campaigning Equally Positive? The Impact of District Level Campaigning on Voter Turnout at the 2010 British General Election

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    A significant comparative literature suggests that campaigning efforts by political parties impact positively, both in terms of mobilization and turnout. However, effects are not uniform. They may be affected by the electoral system used, the electoral circumstances and effectiveness of party management. Studies of district-level constituency campaigning in Britain have identified two important trends. First, that effective targeting is a core component of a successful district campaign strategy in terms of delivering electoral payoffs and that, over time, political parties have become better at targeting resources where they are needed most. While improvements in targeting have helped ensure that all three principal parties’ campaigns have tended to deliver electoral payoffs, a question has arisen as to whether increasingly ruthless partisan targeting by parties could have detrimental effects on overall levels of turnout. Second, they have shown how campaign techniques are continuously being modernised but that, despite these changes, just as in other democracies, more traditional labour-intensive campaigning tends to produce stronger electoral payoffs. This article therefore considers three questions in respect of the impact of district level campaigns on turnout: whether the combined campaign efforts of the three principal parties in Britain are associated with higher levels of turnout; whether the different campaigning styles of parties affect levels of turnout equally; and whether the campaigning efforts of different parties have differential effects on turnout and whether intense partisan targeting does indeed impact upon turnout overall. It shows that while campaigning boosts turnout, the impact varies by campaign technique and by party, as a function not only of targeting but also of electoral context

    You get what you (don’t) pay for: The impact of volunteer labour and candidate spending at the 2010 British general election

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    The published version of this article is fully available from the publisher at the link below.Repeated evidence in Britain demonstrates the positive electoral payoffs from constituency campaigning. However, the impact of such campaigning varies depending upon the electoral context and the effectiveness of campaign management. Debate also exists in respect of the relative impact of traditional versus more modern campaign techniques, as well as between campaign techniques that incur cost and those that are carried out voluntarily. Such debates are of interest not only to academics and political parties, but also to regulators when considering whether to restrict campaign spending in the interests of electoral parity. This article uses candidate spending data and responses to an extensive survey of election agents at the British General Election of 2010 to assess the impact of both campaign expenditure and free, voluntary labour on electoral performance. It suggests that both have some independent impact, but that impact varies by party. The implications of these results are highly significant in both academic and regulatory terms—campaign expenditure can affect electoral outcomes but these effects are offset to some extent by voluntary efforts

    Permutation-Symmetric Multicritical Points in Random Antiferromagnetic Spin Chains

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    The low-energy properties of a system at a critical point may have additional symmetries not present in the microscopic Hamiltonian. This letter presents the theory of a class of multicritical points that provide an interesting example of this in the phase diagrams of random antiferromagnetic spin chains. One case provides an analytic theory of the quantum critical point in the random spin-3/2 chain, studied in recent work by Refael, Kehrein and Fisher (cond-mat/0111295).Comment: Revtex, 4 pages (2 column format), 2 eps figure

    Isostaticity of Constraints in Jammed Systems of Soft Frictionless Platonic Solids

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    The average number of constraints per particle in mechanically stable systems of Platonic solids (except cubes) approaches the isostatic limit at the jamming point (→12 \rightarrow 12), though average number of contacts are hypostatic. By introducing angular alignment metrics to classify the degree of constraint imposed by each contact, constraints are shown to arise as a direct result of local orientational order reflected in edge-face and face-face alignment angle distributions. With approximately one face-face contact per particle at jamming chain-like face-face clusters with finite extent form in these systems.Comment: 4 pages, 3 figures, 4 tabl

    Stability of Elastic Glass Phases in Random Field XY Magnets and Vortex Lattices in Type II Superconductors

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    A description of a dislocation-free elastic glass phase in terms of domain walls is developed and used as the basis of a renormalization group analysis of the energetics of dislocation loops added to the system. It is found that even after optimizing over possible paths of large dislocation loops, their energy is still very likely to be positive when the dislocation core energy is large. This implies the existence of an equilibrium elastic glass phase in three dimensional random field X-Y magnets, and a dislocation free, bond-orientationally ordered ``Bragg glass'' phase of vortices in dirty Type II superconductors.Comment: 12 pages, Revtex, no figures, submitted to Phys Rev Letter

    Numerical Results for the Ground-State Interface in a Random Medium

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    The problem of determining the ground state of a dd-dimensional interface embedded in a (d+1)(d+1)-dimensional random medium is treated numerically. Using a minimum-cut algorithm, the exact ground states can be found for a number of problems for which other numerical methods are inexact and slow. In particular, results are presented for the roughness exponents and ground-state energy fluctuations in a random bond Ising model. It is found that the roughness exponent ζ=0.41±0.01,0.22±0.01\zeta = 0.41 \pm 0.01, 0.22 \pm 0.01, with the related energy exponent being θ=0.84±0.03,1.45±0.04\theta = 0.84 \pm 0.03, 1.45 \pm 0.04, in d=2,3d = 2, 3, respectively. These results are compared with previous analytical and numerical estimates.Comment: 10 pages, REVTEX3.0; 3 ps files (separate:tar/gzip/uuencoded) for figure
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